Description of the user interface

This section will explain the functioning of the program by discussing the main components of the screen.

Figure: overview of the A3D screen

Menu bar

The menu bar contains the following options:

• file:
  • open: opens a new evt file and loads the first event.
  • print: writes a postscript file to disk containing the picture currently in the graphics display.
  • quit: stop the madness

• view: This menu is meant to complement the tree window. It allows turning on or off the following groups of items:
  • photons.
  • lines.
  • oms.
  • hydrophones.
  • tiltmeters.
  Furthermore there are two commands that allow the user to set the point that will be used as centre of the screen (and the origin for rotations):
  • center selection: this centres the graphics screen around the item that is currently selected in the tree window. Also rotations will be relative to this point. (To center around the vertex, select a track and use this option.)
  • center origin: center the graphics screen around the origin of the detector (which is the center of mass of the oms).
• options:
  • reload ini file: All options can be changed by editing the a3d.ini file and reloading it.
  • demo mode: good to impress your friends.
  • render gif: This will create an animated gif file of the current event.

Event Selector

This consists of two buttons that let you go to the previous or next event in the current file. Alternatively a number can be typed in the text window in the middle: if the event with that number exists in the file, it will be loaded.

To allow fast random access of events, A3D maintains a 'database' of the event file. On startup a number of events will be scanned and later on the database will be updated when needed (i.e. when an unknown event number is requested).

relevant parameters in the .ini file

• events_scanned: number of events that will be scanned when opening an event file.

Tree

This is a hierarchical list of all the items that can be displayed The root-node displays the current event file name. Its two sub-nodes represent the event and the detector. Each of these contain more parts.

Switching items on and off

Every item in the tree can be switched on or off by clicking in the little white square. Nodes that contain more stuff can be expanded or collapsed by double-clicking them.

Displaying information on an item

When clicking on a certain item in the tree, information on that item will be displayed in the information window (if available). In particular clicking on the filename will display some information that is found in the run header of the event file.

Showing associated hits

Some tracks have a number of hits associated with them. In the case of Monte Carlo tracks these are the hits that were caused by the track. For reconstructed tracks (and spheres) these are the hits that were used for the reconstruction. To show only the hits associated with a track, one can right-click on the tree-item representing that track. Note that in the view menu there is an option 'show all hits' to view all hits again.

Hit nodes

Hits are accommodated under three nodes: 'muon hits', 'shower hits' and 'k40 hits'. The latter lists all background hits. Hits that are caused by neither muons nor background are listed under the 'shower hits' node; this just means that they were not directly produced by the muon (their particle id in the event file is not 5 or 6). They may be caused by the hadronic shower (for contained events) or by secondary particles (these will have their track-id set to the muon track and a 'photon' will be drawn to that track).

relevant parameters in the .ini file

• colorfull_hit_tree and colorfull_track_tree: When true, the tree-nodes representing hits and tracks will have the same colors as their counterparts in the graphics window.
• use_smartstrings: When true, the tree-nodes representing hits will have some text added to them indicating whether the hit is caused (in the case of a Monte Carlo track) by or used for a track. (s=sphere fit, ps=sphere prefit, r = reconstructed, p=prefit, m=Monte Carlo)

Information window

Here some information is displayed (text) about the currently selected item.

3d Graphics window

Here the three dimensional scene of the current event and detector are rendered.

relevant parameters in the .ini file

• use_back_buffer: This determines the way that the graphical picture is updated. If use_back_buffer is true, the new picture is rendered in a separate piece of memory (called the back buffer) while the old picture is still on the screen. Then, when the new picture is ready, the old picture is replaced by the new one. If use_back_buffer is false, the old picture is erased and the new picture is drawn directly on the screen. This will cause a flickering screen when doing rotations or animations. However this method is much faster when the graphics have to be sent over a network.

3D projection

A3D supports two ways of making a two-dimensional picture of the three- dimensional world: perspective mode and orthogonal mode. In perspective mode, object that are further away from the viewer will appear smaller. Orthogonal mode has the advantage that parallel lines will be drawn parallel and that object size is independent of the objects position.

relevant parameters in the .ini file

• use_perspective: If true 3d graphics will be in perspective mode. If false the orthogonal projection will be used. Each of these is fully configurable by the perspective_xxx and ortho_xxx options respectively.
• use_lighting: If true, a lighting effect is created.

Selection

Selection of an item in the graphics window is done by clicking the right mouse button over (or near) the object of desire. At the moment, you can select only tracks and hits. If the item you selected is currently shown in the tree, the corresponding tree item will be highlighted. Also the info-window will display some information on the selected object.

Moving, Rotating and Zooming

There are two ways to change the view of the detector: Using arrow keys you can walk through the detector. Additional keys are Page up/down which take you up or down. Dragging with the left mouse button rotates the detector around its center (or, when the center selection option from the view menu is used, around the selected object). There is no possibility of zooming. But a similar effect can be obtained by moving the viewpoint towards the place of interest. (however, in orthogonal viewing mode, this is not possible)

NB: it is possible to use the arrow keys while the left mouse-button is down... the program will then be in 'dragging mode' and therefore moving will be faster (if hide_item_xxx_dragging is true for some items).

relevant parameters in the .ini file

• step_size:stepsize for moving trough the detector (cursor up/down and page up/down keys).
• turn_angle:stepsize (radians) for turning (cursor left/right keys).
• hide_xxx_when_dragging, where xxx is some item: When the left mouse button is down, these items will not be drawn. This allows faster rotation of the detector.

Legend for the hit colors

The color of a hit is related to its time. This window makes clear which colors are associated with which times(ns) .

Animation Controls

On speedy computers, A3D is able to show a movie of the event. These controls allow the user to control this animation. At any moment one can start the animation by pressing the 'play' button. The stop button will freeze time. The 'rewind' button will set the time back to the beginning of the animation. Finally the button labelled 'quit' will leave animation mode and A3D will go back to its normal behaviour.

relevant parameters in the .ini file

Please see the section about animation.

Extra Windows

Three small windows on the right of the screen show the detector in an orthogonal projection (i.e. there is no perspective) from the top, the north and the west. These windows are drawn only when a new event is loaded. So when certain items are switched on or off in the main graphics window, these windows will not reflect that change.

relevant parameters in the .ini file

• enable_extra_windows: determines whether or not to draw these windows. When this option is changed A3D should be restarted for the changes to take effect.